连铸单晶铜的力学性能及断裂特征

研究了同纯度的连铸单晶铜和连铸多晶铜的力学性能及断裂特征,并分析了二者范性变形特点的异同及原因。结果表明,连铸单晶铜与连铸多晶铜都没有屈服点,连铸单晶铜与连铸多晶铜相比,具有更好的塑性。连铸单晶铜表现出明显的各向异性,圆柱形拉伸试样变形成椭圆柱形,其长短轴之比为1.36;连铸单晶铜的断口呈扁平状剪切唇口,其断裂机理为微孔长大型断裂,显微孔洞在拉伸轴线上形核。连铸多晶铜宏观断口表现为各向同性和明显的变形不均匀性,在试样的表面出现了凹凸不平的印花,其断裂机理是微孔聚合型断裂,显微孔洞是在以拉伸轴线为对称中心的区域内的形核。

Analysis of Mechanical Properties and Fracture Characteristic of Continuous Casting Single Crystal Copper

Mechanical properties and fracture characteristics of single crystal copper and poly-crystal copper, which are made by continuous casting and have the same purity, are studied in the paper. Their similarities and differences are discussed. The results show that continuous casting single crystal copper and continuous casting poly-crystal copper have no obvious yielding point, but continuous casting single crystal copper is more ductile than continuous casting poly-crystal copper, and continuous casting single crystal copper shows obvious anisotropy, and cylindrical cross section of drawing specimens become elliptical sharp and the ratio of long axis to short axis is 1.36. A typical fracture characteristic is that one microscopic hole appears and grows up on the tensile axis direction. It is the main fracture mechanism of continuous casting copper single crystal. Fracture section of continuous casting poly-crystal copper shows isotropy and asymmetrical deformation. There are some roughness distortion laciniation on the surface of continuous casting poly-crystal copper specimens. The fracture mechanism of continuous casting poly-crystal copper is microscopic holes aggregation model. The microscopic holes nucleus occurs in a region where the tensile axis is symmetry center.